Ultrasonic flip chip bonding process and apparatus

ABSTRACT

A process for bonding a flip chip (20), of the type having an active face provided with conductive bumps, to a substrate (22) so that its active face is oriented toward the substrate (22). The flip chip (20) is coupled through a vacuum to the distended end (32) of an ultrasonic horn (30) and then lowered onto the substrate (22) so that the bumps (20b) align with a bonding pattern on the substrate (22). A bias force is applied through the ultrasonic horn (30) to the backside of the flip chip (20), in a direction normal to the substrate (22) so that minimal lateral displacement of the flip chip (20) and the substrate (22) results. The ultrasonic horn (30) is then activated while the bias force is applied such that the ultrasonic energy is isothermally transferred in a direction normal to and across the flip chip (20) to the substrate (22) for creating a diffusion bond therebetween.

This application is a continuation-in-part of application No.08/239,106, filed May 6, 1994, now U.S. Pat. No. 5,427,301.

TECHNICAL FIELD

This invention relates to an improved apparatus and method for bondingflip chip devices onto a substrate, such as a circuit board. Morespecifically, the invention is a semi-automatic system which enableshigh alignment and bonding accuracy of flipped chips to a substrate.

BACKGROUND ART

Flip chip bonding has emerged as one of the fastest growing technologiesin packaging electronic components. Such technologies have developed inresponse to the demand for circuits which may operate at high speeds inhigh packing densities. Acceptable performance criteria may only berealized by appropriate selection of the substrate, interconnectmechanisms, flip chip design, and the bonding media (manufacturingreliable multi-chip modules).

Several methods may be used to attach a flip chip or die to a substrate.Solder is often used for silicon, aluminum nitride, alumina, or flexiblesubstrates. Gold-to-gold thermocompression or ultrasonic bonding aremainly used for high power small devices. Standard conductive epoxy mayalso be used for flip chip bonding.

Among the issues which need to be considered when designing automatedflip chip bonding mechanisms are placement accuracy, the types of flipchips and substrates, flip chip pickup and placement, substrate pickupand placement, throughput, and price.

Illustrative of previous approaches is U.S. Pat. No. 3,938,722 whichdiscloses an apparatus for bonding flip chip devices onto matingconductive surfaces on a substrate utilizing ultrasonic energy. Thebonding tool has a spherically shaped bonding surface which is caused bya pivoting mechanism to bond in a complex wobbling motion. Suchapproaches, however, may lead to relative lateral motion between theflip chip and the substrate which may jeopardize alignment.

U.S. Pat. No. 4,842,662 discloses a bonding approach wherein no goldglobules or bumps are used in advance of the flip chip connectionprocess. Such gold bumps are typically placed on the terminal pad of theflip chip and on the underside of the wire to be connected to the flipchip. The '662 disclosure, however, relates to single point bondingprocesses adapted for use with tape-automated-bonding (TAB) tape.

U.S. Pat. No. 5,341,979 discloses a thermosonic process for securing asemiconductor die to bonding pads on a substrate using multiple goldbumps. In such a process, heat is applied while ultrasonic energy iscoupled to move the die in the horizontal, rather than vertical, plane.In contrast to this prior art, the process utilized in the presentinvention operates at room temperature, and the ultrasonic energy isdelivered substantially isothermally in the form of verticaloscillations.

SUMMARY OF THE INVENTION

The present invention discloses a process and apparatus for bonding aflip chip to a substrate. The process includes the following steps:

1. positioning the flip chip, coupled to an ultrasonic horn, above thesubstrate, the flip chip having an active face provided with conductivebumps, so that the active face is oriented toward the substrate;

2. lowering the ultrasonic horn for placing the flip chip on thesubstrate so that the bumps align with a bonding pattern on thesubstrate;

3. applying through the ultrasonic horn a force to the back side of theflip chip, the force being normal to the substrate so that minimallateral displacement of the flip chip and the substrate results; and

4. applying a vibration dampening force to areas of the substrateadjacent to the flip chip for reducing the transmission of ultrasonicenergy through the substrate;

5. activating the ultrasonic horn while the force is applied so that theultrasonic energy in the form of oscillations is isothermallytransferred across the flip chip to the substrate and a diffusion bondis created therebetween.

The invention also includes the manufacturing apparatus by which topractice the above-noted process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 is a flow chart of the main process steps of the presentinvention;

FIGS. 2-14 are side elevational views and depict various process stepsand apparatus configurations used in bonding a flip chip to a substrateaccording to the teachings of the present invention;

FIGS. 12a and b are side sectional views showing the positioning of theultrasonic horn, the vibration damper arm and the substrate. FIG. 12c isa top view of the die and the corresponding aperture within thevibration damper arm.

FIGS. 15 and 16 are graphs showing the time sequencing of the bias forceand ultrasonic energy as they are applied to the flip chip.

BEST MODE(S) FOR CARRYING OUT THE INVENTION

The process and method of the present invention represent a system formulti-chip bonding to substrates. The apparatus disclosed can beoperated as an accurate pickup and placement mechanism for registeringthe flip chips in relation to the bonding pattern defined on asubstrate.

By way of overall orientation, the apparatus and process of the presentinvention is used to produce high density packaging applications whichrequire high alignment and bonding accuracy of flipped chips or dies tosubstrates. The apparatus includes one pickup head and one bonding head.The first head picks up the flip chip from a waffle pack, or sawn waferon frame, or tape and reel, and places it on an orientor. The secondhead picks up the die from the orientor and brings it over thesubstrate. Machine vision is used for final alignment when the die isover the substrate. A vibration damper arm isolates the ultrasonicenergy from passing through the substrate and into adjacent dies orcomponents.

As used herein, the term "ultrasonic bonding" includes a solid-stateprocess in which the flip chip is bonded to the substrate by locallyapplying high-frequency vibratory energy thereto while the surfaces tobe joined are held together under bias pressure. It is thought that thediffusion layer may be on the order of 2-3 kilo angstroms in thickness.The disclosed process can be used to bond flip chips to gold, silver,platinum, nickel, or copper metalized patterns on a substrate.

FIG. 1 of the drawings is a flow chart of the main process steps usedfor practicing the process of the present invention.

The flip chip is coupled through a vacuum force to the end of anultrasonic horn and then positioned (10) above the substrate.Conventionally, the flip chip has an active face which is provided withgold globules or bumps. The active face is oriented toward thesubstrate. Next, the ultrasonic horn is lowered to place the flip chipon the substrate (12) so that the bumps align with a bonding patternwhich is formed on the substrate. A bias force is then applied (14)through the ultrasonic horn to the back side of the flip chip so thatthe force is normal to the substrate. In this way, minimum lateraldisplacement of the flip chip in relation to the substrate results. Avibration damping medium is then placed onto the substrate adjacent theflip chip for inhibiting the transfer of vibrations and ultrasonicenergy (16) from the flip chip, through the substrate and outwardly toadjacent electronic devices and other components previously mounted onthe substrate. Finally, the ultrasonic horn is activated (18) while thebias force is applied so that ultrasonic energy is isothermallytransferred across the flip chip to the substrate for carrying adiffusion bond therebetween.

FIGS. 2-14 depict the apparatus and process steps in more detail. FIG. 2depicts the main components of the apparatus used to practice theprocess disclosed and claimed herein. In FIG. 2, a flip chip 20 isloaded onto a flip chip pickup table 24. While a flip chip is describedwith respect to the best mode of the invention, the process may be usedwith a die comprising a variety of materials, such as silicon, gallumarsenede, ceramic, metal, and glass. A substrate 22 (such as an FR4printed wiring board, the base of a multi-chip module, glass, ceramic,or flexible PWB) is positioned upon a work holder 26. In FIG. 3, avacuum flip chip pickup mechanism 28 is extended to pick up the flipchip 20 by use of vacuum.

FIG. 4 shows the vacuum flip chip pickup arm retracted in combination,thus elevating the flip chip 20 above the flip chip pickup table 24. InFIG. 5, a stage 38 which includes the vacuum flip chip pickup mechanism28 and an ultrasonic horn 30 is translated so that the vacuum flip chippickup arm 28 with the flip chip 20 is aligned with a squaring device36.

Next, the vacuum flip chip pickup arm 28 (FIG. 6) is extended to placethe flip chip 20 onto the squaring device 36. The vacuum flip chippickup arm 28 is then retracted (FIG. 7) and the squaring device 36 isactivated to orient the flip chip 20 so that it is square in relation tothe substrate 22.

In FIG. 8, an appropriate distended section 30b is selected from a nest60 and attached through a snap connector 31 to the actuator section 30ato form the ultrasonic horn 30. This coupling is more clearly shown inFIG. 12b. The snap connector 31 includes an O-ring section for sealingthe internal vacuum channel 30a. The snap connector 31 must be locatedat a position that will not adversely interfere with the resonance anddesired vertical motion of the ultrasonic bonding tool 30. Next, thestage 38 is translated so that the ultrasonic horn 30 is aligned withthe squaring device 36. The distended end 32 of the ultrasonic horn 30is then extended (FIG. 9) to pick up the flip chip 20 from the squaringdevice 36 using a vacuum. The distended end 32 of the stainless steelultrasonic horn 30 does not require any special finishing (other thannormal buffing and polishing), hence there is no requirement to "hold"the die 20 against horizontal displacement forces. The vacuum isdelivered through a channel 30c which extends axially through theultrasonic horn 30 to a supply of negative pressure 70. While thedisclosed horn may be used for various flip chip sizes, it is advisableto have the distended end 32 of the ultrasonic horn 30 slightly smallerin size and similar in shape with respect to the die 20.

In FIG. 10, the ultrasonic horn 30 is shown as being retracted whilecarrying the flip chip 20 along with it. In FIG. 11, the stage 38 istranslated so that the ultrasonic horn 30, together with the flip chip20, is aligned opposite a known bonding location 48 defined upon thesubstrate 22.

In FIG. 12, a means for alignment, such as an optical device 34, istranslated to a location between the flip chip 20 and the substrate 22.Precise alignment of the flip chip 20 in relation to the substrate 22then commences by manual or automatic means. Although an optical meansfor aligning has been disclosed, other alignment means may be used, suchas split prisms and infrared techniques. After proper alignment of theflip chip 20 is achieved with the fine line conductor traces on thesubstrate 22, the optical alignment device 34 is moved into a storagelocation away from the bonding location 48 on the substrate asillustrated in FIG. 12a.

As illustrated in FIG. 12A, a vibration damper arm 40 is moved intoposition directly above the known bonding location 48. As illustratedmore clearly in FIG. 12B, the vibration damper arm 40 has attached tothe underside thereof a rubber pad 42 that is deformable when verticallycompressed onto the substrate 22. As illustrated in FIG. 12C, both thevibration damper arm 40 and the rubber pad 42 have defined therein anaperture 44 which is sized and shaped to be just slightly larger thanthe die 20 and the distended end 32 of the ultrasonic horn 30. In thismanner the die 20 may be inserted through the aperture 44 withoutdisturbing the location or alignment of the die 20 with respect to thecircuit traces at the known bonding location Note that in FIG. 12B thedamper arm 40 and the rubber pad 42 remain spaced above the substrate22. The damper arm 40 is formed with a horizontally disposed aluminumplate approximately four inches square and 0.25 inches thick. The rubberpad is approximately 0.10 inches thick and is laminated to the undersideof the plate. A pneumatic mechanism employing an air piston is coupledto a slide bearing which allows the damper arm 40 to be extendedvertically to engage with the substrate 22. While the damper arm 40 isillustrated separately from the carrier 38 for the ultrasonic horn 30for sake of clarity, in the preferred embodiment the damper arm isactually fixed to and moves with the carrier 38 for the ultrasonic horn30.

FIG. 13 depicts extension of the ultrasonic horn 30 to bring the flipchip 20 into contact with the substrate 22. A predetermined initial biasforce of approximately 10 pounds per square inch is then applied by theultrasonic horn 30 to press the die 20 against the substrate 22 in knownregistration. In the preferred embodiment it will be assumed that thedie 20 comprises a 300 mill by a 300 mill silicon die having a total of144 gold bumps on the lower side thereof for being attached tocorresponding traces in the substrate 22 which are approximately 5 milsin width and having a gap of 1 mill therebetween. The bump sizes areapproximately 5 mils square.

After this initial bias force, which may be fixed or varied as afunction of time, is impressed upon the die 20 to secure it in knowregistration against the substrate 22, the vibration damper arm 40 islowered such that the rubber pad 42 deforms around adjacent electricalcomponents and die, as shown more clearly in FIG. 13B, so as to pressfirmly against the substrate 22. Since the size of the aperture 44within the vibration damper arm 40 and the rubber pad 42 is larger thanthe die 20, the proper registration between the bumps on the underneathside of the die 20 should not be disturbed with respect to the circuitconductors on the substrate 22. The rubber pad 42 is sufficiently softsuch that a force of only approximately 25 pounds per square inch willdeform the rubber pad 42 around adjacent die and electrical componentsthat have been previously placed on the substrate 22. However, therubber pad 42 is sufficiently stiff and resilient so that it will absorbor dampen a major portion of the ultrasonic energy that is conductedfrom the ultrasonic horn 30 and through the die 20 and into thesubstrate 22. In this manner, the ultrasonic energy will not betransferred to the adjacent die and electrical components which couldcause delamination of the various bonds, as will be discussed in moredetail subsequently.

After the damper arm 40 is secured against the substrate 22, ultrasonicenergy, within a range of 30,000 to 100,000 oscillations per second(with the preferred embodiment utilizing a 60,000 Hz frequency), isapplied to the backside of the flip chip 20 for a predetermined timeperiod of up to about 10-20 seconds as illustrated in FIG. 13A. Tocomplete the cycle (FIG. 14), the damper arm 40 and then the ultrasonichorn 30 retract, leaving the gold bumps 20b on the flip chip 20 joinedto the substrate 22 by a secure diffusion bond.

X-ray photographs (not shown) of a flip chip 20 poised above a substrate22 reveal a rectangular gray area is the backside of the substrate 22.In the aligned configuration, each dot represents a gold globule bumplocated on the active face of the flip chip 20. Extending away from thegold bumps is a bonding pattern which is defined by gold plated circuittraces or leads defined on the top surface of the substrate 22.Alignment or registration is enabled by the alignment device. Using thedisclosed process and apparatus, all of the bumps disposed upon the flipchip are diffusion bonded simultaneously to the bonding sites definedupon the substrate.

As illustrated in FIG. 13C, the plurality of gold bumps 20b are bondedto the conductive paths 20p, typically manufactured of aluminum orcopper, on the lower side of the die 20. Since the gold bumps 20b aregrown on the aluminum pads 20p of the semiconductor die 20, theultrasonic energy used to bond the flip chip also affects the gold toaluminum interface and creates gold-aluminum intermetallic formations.These intermetallic formations range from the gold rich to the aluminumrich, among them the well known purple plague (AuAl₂) and the whiteplague (Au₅ Al₂) intermetallic formations. Also, Kirkendahl voids, whichare delaminations of the gold to aluminum interface, may be formed atthis bonding interface. During the ultrasonic bonding process, theprofile of the application of the bias force and the ultrasonic energycan be controlled so that the optimum bonding can be obtained and theseundesirable affects can be avoided.

However, in the case where multiple flip chips are bonded sequentiallyonto the same substrate, the ultrasonic energy which is undesirablycoupled into adjacent flip chips bonded previously onto the substratecan alter the intermetallic formations and cause the Kirkendahl voids tooccur on these previously attached components. These failure modes areof special concern when the ultrasonic energy is applied normal, ratherthan horizontal to, the plane of the substrate. The damper forces usedin the present invention substantially eliminate these undesirableside-effects.

Since the ultrasonic energy transfers through the vertical displacementof the ultrasonic element 30, it will be absorbed in large part by theformation of the intermetallic bonds between the die 20 and thesubstrate 22, rather than being lost due to the planar displacement ofthe die and the slippage between the die and the ultrasonic element thatwould take place if the ultrasonic motion would be in the horizontalplane. As a result, a relatively smaller amount of ultrasonic energy isrequired to complete the bonding when the motion is normal to thesubstrate 22. As used herein, the term normal to the substrate 22 shouldalso imply that the ultrasonic motion will be normal to the horizontalplane of the die 20, since in typical operations the plane of the die 20is parallel to the plane of the substrate 22.

The vertical ultrasonic bonding motion greatly reduces chip displacementfound when the ultrasonic motion displaces the chip in the horizontalplane. Therefore, more accurate placement of the die 20 will allow theuse of smaller fine-line geometries between the die 20 and the substrate22 than is possible for processes using horizontal displacement.

Furthermore, since the ultrasonic motion is in a plane normal to thesubstrate 22, the distended end 32 of the ultrasonic tool 30 does nothave to be custom designed to engage and hold the die 20 as is necessaryfor horizontal displacement processes. Therefore, the entire range ofdie sizes, that is from approximately 100 to 500 mils, can be coveredusing only approximately three ultrasonic elements that are pre-tunedand quickly interchangeable. This compares with the expense and timerequired to tune the natural frequency of the ultrasonic tools used inhorizontal displacement systems which must take into account the mass ofthe horn and the attached die.

In practice, when the ultrasonic horn 30 is activated, microscopicsurface contaminants and oxides are dispelled from the flip chip and thesubstrate, thereby producing an atomically clean surface for bonding.

As illustrated in FIG. 15, when the bias force 80 is applied to the flipchip 20, it is applied in stages. First, an initial bias force 80a of,for example, 5-10 pounds is applied (shown as the first plateau in thedashed line), followed by a second force 80b of up to 15-25 pounds.These forces are generated by electromagnetic transducers that can betransitioned (slewing) between the two pressures with a preferredramping wave-form. As illustrated in FIG. 15, the initial period ofultrasonic energy 90a is applied for only approximately 3 seconds, whichis about the first one-third of the approximately 10 second bondingperiod. This initial period of lower energy bonding 90a produces a"tacking bond" or "mechanical bond" that is sufficient to assist inholding the die 20 firmly in place with proper registration to thesubstrate 22 during the final or higher power bonding process 90b. Afterthe higher pressure static force 80b is exerted upon the die 20 by theultrasonic horn 30, the increased ultrasonic energy 90b is transferredto complete the full diffusion bonding process (also known as a "coldweld"). This higher energy bonding is required in order to permanentlybond the die 20 onto the substrate 22. Of course, these bonding profileswill change depending on the die size, the number of bumps, and thematerials used in the bumps.

This unique sequential profile of multiple force and energy levels,beginning at low values and moving to higher values, creates asignificantly more reliable bond, as well as reducing misalignmentbetween the die and the substrate. If the full ultrasonic energy 90bwere to be applied at the beginning of the process, the die wouldvibrate and thereby cause potential misalignment and damage to the bumpson the die or the substrate circuit traces. This failure mode isentirely eliminated by the profile illustrated in FIG. 15 whichsequentially increases the clamping force and ultrasonic energy.Furthermore, this pressure and energy profile avoids many of theover-bonded and under-bonded failure modes observed in horizontaldisplacement bonding processes.

An alternative multi-level force and energy profile is illustrated inFIG. 16. According to this profile, the static compression force fromthe ultrasonic horn 30 ramps up sharply 80c until the initial lowerlevel ultrasonic energy 90c is applied, and then the rate of increase ofthe static force is reduced 80d, although it still is increasing. Afteran initial "tacking period", the level of ultrasonic energy is increasedrapidly 90d to a higher final bonding level 90e. The bias pressure ofthe ultrasonic horn 30 against the die 20 need not be increased furtherafter it reaches plateau 80c, during which the higher level ofultrasonic bonding energy is transferred. It should be apparent to oneskilled in the art that various multi-level bonding profiles may beutilized depending upon the size and shape of the die, the number ofbumps, etc.

As illustrated in FIG. 13D, the ultrasonic forces induced by theultrasonic horn plastically deform the gold bumps adjacent a region ofcontact between the flip chip and the substrate so that an intimatecontact therebetween results and an intermetallic atomic bond is formedby isothermal ultrasonic energy. In practice, if there are three bumpsper flip chip, a 1-2 pound force should suffice. If there are 250 bumps,for example, a force of 25-30 pounds should suffice if applied for aperiod of up to about 10-20 seconds, with 10 seconds being used in thebest mode of the present invention.

With continuing reference to FIG. 13D and to FIG. 13C, the precisecontrol of the pressure and ultrasonic energy profiles are helpful incontrolling and eliminating any delamination that can occur in theintermetallic bonds that are used to construct the pads 22p on thesubstrate 22. The typical gold pad 22p includes a base layer of copper(approximately 1-2 mils), onto which an intermediate layer of nickel isplated (approximately 100-200 micrometers), followed by the final layerof soft gold (approximately 30-50 micrometers). It has been found thatexcessive absorption of the ultrasonic energy by this complex metallicstructure, as located on die that had been bonded adjacent to theenergized work area, may delaminate and fail due to the additionalenergy conducted by the substrate 22 and absorbed by the intermetallicinterfaces. The same general failure modes are also observed in thecomplex intermetallic formations (Al_(x) Au_(y)) that hold the gold bumpto the aluminum trace that traces on the die 20.

The vertical displacement process of the present invention is superiorto those prior art processes requiring horizontal displacement becausethese prior art processes typically require the application of heat toeither the die, the substrate or both. The addition of this supplementalheat energy further increases the probability of the intermetallicfailures between the substrate, the gold bump and the die.

Thus, it will be apparent that the disclosed process and apparatusrequires no heat, no solder, and is quick. Since no heat is required,the apparatus and process can be used for heat sensitive substrate flipchip bonding media and produces less damage to the flip chip compared tothermocompression bonding or solder reflow. Throughput is enhancedbecause an entire flip chip can be bonded to a substrate regardless ofthe number of connections. Finally, since all forces are in the vertical(Z) direction, there is no relative horizontal movement between the flipchip and the substrate.

In practice, substrates up to about 14 inches square may be accommodatedwithin the disclosed apparatus. Flip chips as small as 0.05 inchessquare may be handled. Flip chips 1 inch square may also be effectivelyused by the disclosed process.

The disclosed invention not only improves bonding accuracy but alsofacilitates throughput because the pickup tool is also the bonding tool.This eliminates the need to place, retract, and engage the flip chipwith the horn. The disclosed apparatus is a semi-automatic system forproducing high density packaging applications which require highalignment and bonding accuracy of flipped chips to the substrate.

While the present preferred embodiment has been described with referenceto gold bumps 20b that are bonded to the die 20, it should be apparentthat the bumps may be formed from any deformable and fusible materialthat will create long-lasting intermetallic with the adjacent materials.Gold is preferred because it will not oxidize and is especially workablein the diffusion bonding process as described herein. However,appropriate adjustments in the bonding profile and metal substrates canbe employed to bond flexible cables to the substrate and the die or toform a cable to cable bond using essentially the same process asdisclosed herein.

The ultrasonic transducer and horn of the disclosed apparatus may bemanufactured in various forms. One suitable vendor is Uthe Technology ofMilpitas, Calif. The disclosed ultrasonic transducer and horn is a model506 FO, which may be driven at the 6 watt and then the 20 watt powerlevels in the profile shown in FIG. 15.

One type of flip chip attachment apparatus is manufactured by R DAutomation of Piscataway, N.J. (Model AFC-101-AP). The machine producesalignment accuracy of better than ±5 microns. Throughput levels up to350-500 flip chips per hour are possible depending upon the processparameters. In one system (M-8 flip chip bonder), a thin optical probeis inserted between the flip chip and the substrate, imaging bothbonding surfaces simultaneously. Two video cameras and reflectionilluminators are used to view the flip chip and the substrateindividually. Outputs of the video systems are superimposed on onescreen and the alignment is achieved by moving the substrate inreference to the stationary flip chip. Final alignment is performed whenthe flip chip is in close proximity to its final position, after whichthere is no motion in the X, Y, or theta directions. The only axes uponwhich motion may remain is in the vertical (Z) direction.

Although the present invention has been described in conjunction withthe best mode of its process and the preferred embodiment of theapparatus, one skilled in this art will understand that other equivalentimplementations are intended to be covered, and not limited by, thefollowing claims.

We claim:
 1. A process for bonding a flip chip to a substrate havingcomponents mounted thereon, comprising:positioning the flip chip,coupled to the distended end of an ultrasonic horn, above the substrate,the flip chip having an active face, provided with conductive bumps, sothat the active face is oriented toward the substrate; lowering theultrasonic horn for placing the flip chip on the substrate so that thebumps align with a bonding pattern on the substrate; applying throughthe ultrasonic horn a bias force to the backside of the flip chip;applying a vibration dampening force to the substrate adjacent the flipchip for reducing the transmission of ultrasonic energy through thesubstrate to adjacent components; and activating the ultrasonic horn sothat the ultrasonic energy in the form of oscillations is applied withthe oscillations oriented generally normal to the substrate, theultrasonic energy being is isothermally transferred across the flip chipto the substrate for creating a diffusion bond therebetween.
 2. Theprocess of claim 1, wherein the activating step comprises deliveringultrasonic energy within a range of 30,000 to 100,000 oscillations persecond.
 3. The process of claim 1, further comprising the step of usingthe ultrasonic energy for dispelling microscopic surface contaminantsand oxides from the flip chip and the substrate, thereby producing anatomically clean surface for bonding.
 4. The process of claim 1, furthercomprising the step of plastically deforming bumps adjacent a region ofcontact between the flip chip and the substrate so that an intimatecontact therebetween results and an intermetallic atomic bond is formed.5. The process of claim 1, wherein the positioning step includesaligning the flip chip with the bonding pattern on the substrate byoptically aligning the flip chip and the substrate so that the bumps areindexed with a corresponding bonding pattern on the substrate before thelowering and force application steps.
 6. The process of claim 1, whereinthe step of applying a force to the flip chip comprises the step ofapplying a force up to 50 kilograms.
 7. The process of claim 6, whereinthe step of applying a force to the flip chip comprises the step ofapplying a force up to 20 seconds.
 8. The process of claim 1, whereinthe step of applying the bias force includes the step of aligning thebias force normal to the substrate so that minimum lateral displacementof the flip chip and substrate results.
 9. The process of claim 1,wherein the positioning step further includes the step of vacuumcoupling the backside of the flip chip to the distended end of theultrasonic arm before positioning the flip chip onto the substrate. 10.The process of claim 1, wherein the step of applying a vibrationdampening force further includes the step of absorbing a significantportion of the ultrasonic energy before transmission to and disruptionof diffusion bonds coupling adjacent components to the substrate.